Thank you for all your tips. I will work this weekend on adjusting the mix on both my 420SEL and my daughter's 300TE. Now that it is getting warm here in so. California, this is a good time to do this procedure.
Tkamiya, I found out the "hard" way about the in-fender resorvoir. While replacing the external overflow tank in my daughter's wagon I also decided to replace the top, overflow hose (it was old and ratty looking) hose. I had assumed (silly me)
that it was just a hose going into the fenderwell to drain to the outside. Hah! After looking around I decided to remove the fender...no, not the fender
just the fender lining...I discovered the real overflow tank...:p
Well, I replaced the hose and everything is now nice and new...so all I have left to do is to change the coolant/water ratio
Again, thanks for all your help....